Automatic positioning means for machine-tool supports and other supports



y 24, 1951 A c B DE VLlEG ETAL 2,561,346

U'IOMATIC PO'SIT'IONING MEANS FOR MACHINE TOOL SUPPORTS AND OTHER SUPPORTS Filed Aug. 2, 1945 7 Sheets-Sheet 1 INVENTORS CHARLES B. DeVLl EG BY EUGENE E. STEGNER a Y ATTOR N EYS y 24, 1951 'c B. DE VLIEG ETAL 2,561,346

AUTOMATIC PO SITIONING MEANS FOR MACHINE TDOL SUPPORTS AND OTHER SUPPORTS Filed Aug. 2, 1945 '7 Sheets-Sheet 2 -In r4 "is I I II: I; In 9 o I 4g ----q III .I I sotfij I7 ITI I IwI LITZ

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I I I l I I I I I I I I I I I A lzofij I I I I I I I I I I I I I I I I I I I I IDI 4 F I d F to (5i 3 INVENTORS CHARLES B DeVLIEG BY EUGENE E. STEGNER ATTOR NEYS y 24, 1951 c. B. DE VLIEG ET AL 2,561,346

AUTOMATIC POSITIONING MEANS FOR MACHINE TOOL SUPPORTS AND OTHER SUPPORTS Filed Aug. 2, 1945 7 SheetsSheet 5 FIG 2 4 IN I- 'EN TORS CHARLEs B. DeVLlEG BY EUGENE E. STEGNER ATTORNEYS July 24, 1951 c, 5, VLIEG ET AL 2,561,346

AUTOMATIC POSITIONING MEANS FOR MACHINE TOOL SUPPORTS AND OTHER SUPPORTS Filed Aug. 2, 1945 7 Sheets-Sheet 4 IN V EN TORS CHARLES B. DeVLlEG BY EUGENE E. STEGNER ATTORN EYS July 1 c. B. DE VLIEG ETAL AUTOMATIC POSITIONING MEANS FOR MACHINE TOOL SUPPORTS AND OTHER SUPPORTS '7 Sheets-Sheet 6 Filed Aug. 2, 1945 w e m. mm" QQ T. Ne m m qu 5 W. B E S E E d5 A G 1 awn W W. Y W

B mm c m n5 mm Will]! g 8 8 3 3o 8 68 Y 5 68 O N DE Smd om N DE Hm o 5 Si ATTORNEYS ly 2 1951 c. B. DE VLIEG ETAL AUTOMATIC POSITIONING MEANS FOR MACHINE TOOL I SUPPORTS AND OTHER SUPPORTS 7 Sheets-Sheet 7 Filed Aug. 2, 1945 INVENTORS R mw m V E e T D 8 B N avg L E R u AMG H U a G E W Z R 5 M MTQRNEYS Patented July 24, 1951 AUTOMATIC POSITIONING MEANS FOR MACHINE-TOOL SUPPORTS AND OTHER SUPPORTS Charles B. De Vlieg, Farmington, and Eugene E. Stegner, Detroit, Mich.; said Stegner assignor to said De Vlieg Application August 2, 1945, Serial No. 608,452

34 Claims.

The present invention relates to improvements in machine tools, such, for example, as milling machines and boring machines, and more particularly to improved apparatus for automatically etlecting movement of the tool and work supports into preselected relative positions with precision accuracy. However, the invention is applicable to the movement of any support, carrier, or the like, where precision positioning is desired.

One of the major problems involved in precision machine tool work is that of accurately positioning the work and tool supports relative to each other in performing successive and precisely spaced operations on a work piece, and of re-establishing a preselected position of either support after the support has been moved away from the preselected position to permit inspection of the work piece. In the main, conventional machine tools are only equipped for manual positioning the tool and work supports, such positioning being accomplished by crank operation of lead screws threaded into screw followers carried by the supports. Such machines require the use of precision blocks and micrometer indicating gauges in establishing the desired support positions, and thus require a high degree of skill on the part of the machine operators if accurate work is to be produced. Electric powered machines of the character described and employing electric motors for driving the tool and work supports have also been used commercially. In general, however, such machines have not been altogether successful, due in part to the diillculties involved in cutting the motor power at the precise instant required for stopping a tool or work support in the exact preselected position. Thus, during motor drive of a machine work support, for example, considerable kinetic energy is stored in the moving parts, certain of which, notably the work support, work piece and motor rotor, may have considerable mass. This stored energy effects continued or carry-over movement of the support after the driving motor is deenergized. The extent of carry-over is, of course, dependent upon several factors, principally the speed at which the support is moving at the time the motor power is cut, and it is for this reason that such machines usually embody both a rapid traverse motor for first moving the support rapidly toward a preselected position and a feed motor for slowly eflecting final movement of the support into the preselected position.

It has been found that the lack of accuracy in support positioning in machines of the electric powered type is largely due to two factors, 1. e. failure accurately to anticipate the magnitude of the carry-over movement coupled with the fact that in such machines the position responsive motor control circuits are designed to stop the support only in response to single direction movement of the support. Further errors in support positioning are introduced by failure to relax the driving connection between the feed motor and support after positioning of the support is eifected and before clamping the support against further movement. Thus forces acting upon the support through the motor drive mechanism causes a slight shifting of the support position as to the clamping operation proceeds.

Furthermore, prior positioning means, both hand and power operated, are affected by such conditions as the presence of tight gibs and poorly lubricated ways which make for irregular and jerky movement of the support, resulting in inaccurate position thereof; also, stored-up stress on the gearing and driving train at the critical time of positioning is a factor contributing to inaccuracy because ordinarily vibration in the machine tends to relieve this stress and disturb the support setting unknown to the operator; also, such prior methods depend on skill and accuracy of the operator in reading the indicator dial and in manually operating the setting with the result that variables and inaccuracies are apt to occur, particularly when repositioning the support to a previously determined position. The present invention contemplates automatic positioning and repositioning to a high degree of precision in a manner overcoming such variables and inaccuracies as are here described.

It is an object of the present invention, therefore, to provide improved motor powered facilities for automatically positioning the tool or work support of a machine tool in a preselected position with a high degree of precision accuracy.

It is another object of the invention to provide machine tool support positioning facilities of relatively simple arrangement which may be easily controlled and are completely reliable in operation.

It is a further object of the invention to provide either the work support or the tool support in either direction to any desired position other than the preselected support position.

The invention, both as to its organization and method of operation, together with further obsential parts of a combined milling and boring machine having embodied therein automatic work support and tool support positioning means characterized by the features of the present invention;

Fig; 2 is a rear elevational view in partially schematic form illustrating the mechanical construction of the machine;

Fig. 3 is a top plan view of the machine shown in Figure 2;

s Fig. 4 is a side view, partially in section, illustrating the drive mechanism embodied in the machine;

Fig. 4A is an enlarged fragmentary view, partially in section. illustrating further details of the clutch and clutch actuating mechanism forming a part of the drive mechanism shown in Figure 4; a

Fig. 5 is a fragmentary side view in elevation illustrating the position indicating and gauging facilities provided in association with the work support of the machine shown in Figures 2 and 3;

Fig. 6 is a top view partially in section of the position indicating and gauging facilities shown in Figure 5;

Fig. 7 is a fragmentary sectional view taken approximately along the lines |1 in Figure 5;

Fig. 8 is a sectional view taken along the lines 8-! in Figure 6;

Fig. 9 is a sectional view taken along the lines 9-9 in Figure 6;

Fig. 10 is a side view of the gauging and position indicating facilities provided in association with the tool support of the machine;

Fig. 11 is a sectional view taken along the lines il-ll in Figure 10; and

Fig. 12 is a graph illustrating the manner in which either of the two supports may be moved precisely to a preselected position under the control of the prment improved positioning facilities.

Referring now to the drawings and more particularly to Figure 1 thereof, the present improved positioning means are there illustrated in their embodiment in a combined milling and boring machine of the character shown in the application of Charles B. De Vlieg, Serial No. 460,111, filed September 29, 1942, now Patent 2,391,398. Briefly, this machine comprises a work support in the form of a horizontally movable work table It, and a vertically movable tool support l2 which carries a rotatable tool spindle |2a for receiving a boring tool for operating upon a work piece I i clamped or otherwise fixedly mounted upon the work support ID. A lead screw 30 threaded through a screw follower II mounted upon the work support iii at the underside thereof is utilized to convert rotary movement of the screw into horizontal movement of the work support III relative to the tool support l2. Similarly, a lead screw shaft 34 threaded through a screw follower embodied in the tool support I2 is employed to eflect vertical movement of this support relative to the work support M. For

the purpose of effecting rapid traverse or high speed movement of either of the two supports II and I2, a three-phase, reversible and two-speed motor I3 is provided having high speed terminals and low speed terminals 46 arranged for selective and reversed phase energization from a three-phase alternating current feeder circuit indicated by the bracketed terminals It. In order to eflect slow speed feed movement of either of the two supports Ill and I2 into a preselected position, a two-speed, reversible and three-phase alternating current motor I4 is provided'having high speed terminals 48 and low speed tersprockets l8 and I9 and a chain H to be driven' by the rapid traverse motor 13. This shaft may also be driven by the feed motor ll through a driving connection afforded by a worm screw 42, a worm gear 42 and a clutch mechanism l4 best shown in Figure 4A. As pointed out more fully below, this clutch mechanism is so controlled by a clutch actuator indicated generally at 2i that the clutch connection between the worm gear 43 and the shaft 20 is broken so long as torque is developed through energization of the rapid traverse motor l3. Rotary movement of the shaft 2| may be selectively transmitted to a shaft 28, utilized in driving the vertical lead screw 34 to move the tool support l2, or to a gear 25, utilized in driving the horizontal lead screw 30 to eflect movement of the work support ill, through a manually settable transmission mechanism 24 which comprises a pair of relatively slidable gears 22 and 23, the first of which is mounted for rotation with the shaft 20 and the second of which is mounted for rotation with a clutch sleeve 24a freely rotatable about the shaft 20. This sleeve is arranged for sliding movement in either direction along the shaft 26 under the control of a rockable actuator 40 having an actuating element ll riding within an annular recess within the sleeve 24a. At its two opposed ends, the sleeve 24a is provided with clutch teeth respectively engageable with the facing teeth of a clutch member 240 mounted for rotation with the shaft 26 and a clutch member 24b rotatable relative to the shaft 26 and formed integral with the gear 25. The shaft 26 is connected in driving relationship with the lead screw ll through a connection, described below, which includes a pair of engaged bevel gears 32 and 33. Similarly, the gear 25 is connected in driving relationship with the lead screw so through a gear 21 mounted for rotation with an idler shaft 35 and meshing with a gear 28 mounted for rotation with the lead screw shaft 30. Manual adjustment of the work support Ill may be effected through rotation of a shaft 38 which is provided with a bevel gear 31 meshing with a bevel gear 38 mounted for rotation with the idler shaft 3. At its extended end, the shaft 38 is provided with flattened sides 29 receivable within the correpondingly shaped opening of a manually operable crank. Similarly, manual adjustment of the tool support l2 may be eifected through rotation of a crank shaft 29 which is connected in driving relationship with the shaft 26 through the gears 8 20d, and 20c, the shaft 20c and the bevel gears 22c and 20b.

During operation of the machine in the manner described below, the desired control of the control circuit 50 is, during positioning of the work support III, in part eflected through operation of a stationary limit switch which is actuated each time the work support I0 is moved through a particular preselected position. Similarly, the control circuit 50 is in part governed by a limit switch 68 movable with the tool support I2 during movement of this support into a desired preselected position. These two switches are each of the well-known Microswitch type, each being instantly and delicatelyresponsive to inflnitesimally small movements of its actuating element 60a, 1. e. movements of the order of .0003 inch. Actuation of the switch 50 in response to movement of the work support I0 through a preselected position is eil'ected through actuation of a lever mechanism indicated generally at 01 which is operated when engaged by adjustable gauging means movable with the work support I0. Speciflcally, the gauging means, which may be adjustable as desired to preselect the particular position to which the work support I0 is to be moved, may comprise one or a plurality of adjustable micrometer rods 66 disposed in a trough 63b of a rail '63 movable with the support I0, and a micrometer spindle 65 threaded through a spindle support 64 fixedly mounted upon the trough 03. Similarly, actuation of the Microswitch 60 in response to movement of the tool support l2 through a desired predetermined position is effected under the control of gauging means comprising one or a plurality of adjustable micrometer rods II and an adjustable micrometer spindle 13 threaded through a part ll of the column which supports the tool support I2 for vertical movement.

In addition to the Microswitches 60 and 68, the electrical control circuit 50 comprises a group of contactors I20, I30, I40, I10, and I80, and a pair of magnet actuated adjustable timing devices I60 and I80 which are commonly controllable by an automatic positioning switch 59 of the self-restoring type and are selectively controllable by the two identified Microswitches to control the motors I3 and It in effecting movement of either the work support l0 or the tool support I2 to a desired preselected position. A manually operable and non-restoring selector switch 54 is utilized selectively to render the Microswitches 60 and 00 active in controlling the described contactors and timing devices. Operation of the rapid traverse motor I3 to produce rapid traverse movement of the work support I0 to the left or the tool support I2 upward is effected under the control of a contactor I00 which is arranged for selective energization through a self-restoring push button switch 51 and a limit switch 5i. This limit switch is arranged for operation to its open circuit position when the work support I0 is moved to its extreme position to the left. Energization of the rapid traverse motor I3 to produce rapid traverse movement of the work support III to the right or the tool support I2 downward is under the control of an additional contactor I50 arranged for energization through the contacts of a self restoring push button switch 50 and the contacts of either the Microswitch 00 or the Microswitch 68. A limit switch 53 arranged for actuation to its open circuit position in response to movement of the work support I0 to its extreme right position is also provided in the control circuit to prevent possible continued energization of either of the two motors I3 and it after the work support I0 has been moved to the extreme right limit of its range of travel. Similarly, a limit switch 52 is provided in the circuit to prevent movement of the tool support I2 be- Yond the lower-most limit of its range of travel.

The machine construction In general, the construction of the machine in which the present improved support positioning facilities are provided is substantially as shown in the De Vlieg application abovementioned, but it should be understood that this is only for purpose of illustration and that the invention is applicable to machine tools generally, wherever precision positioning of support members is desired. Briefly. and referring particularly to Figures 2 and 3 of the drawings, the machine comprises a bed having vertically aligned and horizontally spaced ways 80a and 80b along the top thereof upon which the work support I0 is slidably supported for movement in a horizontal plane. This support is of twopart construction, comprising a lower member Illa (commonly termed a saddle) directly slidably supported upon the ways 80a and 80b. and provided with horizontally spaced slide ways Ilc which slidably support a top member I0b (commonly termed a work table or platen) for movement in a horizontal plane but at right angles relative to the line of movement of the saddle I0a relative to the bed 80. The bed 80 also fixedly supports the usual vertical column 0| upon which the tool support I2 is slidably mounted for up and down movement in a vertical plane by means of ways Bla and 8Ib integral with the column 8i and slide members I21; and In forming a part of the support I2 and defining ways for slidably receiving the ways Ma and llb. In this instance the driving mechanism is mounted upon the bed 80 at a level below the work support I0. Specifically, and as best shown in Figure 3 of the drawings, this mechanism is disposed substantially centrally between the sides of the bed 80, and the manually adjustable shafts 29 and 38 for respectively manually positioning the work and tool supports are brought out through one side of the bed. The tool support actuating shaft 26 extends longitudinally of the bed 00 and carries a bevel gear 26b which meshes with a bevel gear 260 carried by a second shaft 26a. The latter shaft mounts the bevel gear 32 through which rotary movement is imparted to the lead screw 34 utilized in vertically positioning the tool support I2.

The driving mechanism 15 Referring now more particularly to the structural arrangement of the driving mechanism I5, the manner of rotatably supporting the various elements of this mechanism will be readily apparent from a consideration of the bearing and housing assembly illustrated in Figure 4 of the drawings. As there shown, the gear 23 through which rotary motion is selectively imparted to the lead screw 30 and the horizontal drive shaft 26, is integrally formed with the clutch member 24a, which latter member is slidably and rotatably supported upon a sleeve 24d carried by a rotatable shaft 26c. At its right end this shaft is journaled within a bearing 26f, the outer race of which is mounted for rotation with the clutch part 240. This clutch part is in turn pinned or keyed to the left end of the shaft 26 for rotation therewith. The movable clutch member 24a asenssc 7 may be moved to the left from its illustrated neutral position to bring the clutch teeth at the left end thereof into engagement with the teeth of the clutch part 24b by suitable actuation of the actuator element 4| which connects with the actuator 40. Conversely, by sliding the movable clutch part 24a to the right from its illustrated neutral position, through suitable reverse actuation of the actuator element 4|, the teeth at the right end of the clutch part 2411 are brought into clutching engagement with the teeth of the clutch part 24b to establish a driving connection with the shaft 20.

Briefly, to consider the structural arrangement of the clutch 44 and clutch actuator 2I through operation of which the feed motor I4 is selectively rendered operable to drive the shaft 20, it is first pointed out that the worm gear 43 driven from the worm screw 42 of the feed motor rotor shaft is keyed to a sleeve I02 (Figure 4A) which at its left end is provided with clutch teeth I32a. These teeth are engageable with the teeth 91a of a second clutch sleeve 31 which is slidable longitudinally of the shaft 20 and is keyed cr splined thereto as indicated at 93. The clutch sleeve 91 is provided with an integral oppositely extending sleeve portion 91b which extends into and is freely rotatable within the sleeve I02. At its right end this sleeve abuts the left end of a clutch actuator I03b having a sleeve portion I03a which also extends within the sleeve I02 and is rotatable relative to this sleeve. Like the clutch sleeve 91, the actuator sleeve I03a is splined to the shaft 20 for rotation therewith by means of the splines 00. At its right end the actuator I03 is provided with clutch actuator jaws I03b engageable with the Jaws I04 of a clutch actuator sleeve I3a upon which the sprocket I9 is mounted. Specifically, the jaws I03b and I04 are provided with two sets of engageable camming surfaces I03c, Illla and I03e, I040 utilized in effecting movement of the sleeves I03 and 91 to the left to effect disengagement of the clutch teeth 91a and I02a. The jaws I03!) and, I04 are also provided with two sets of engageable stop surfaces I03d, I04!) and I03f,.I04d having the function of transmitting torque from the sprocket I3 to the shaft 20 through the parts I03 and 90. Normally, the clutch teeth 91a and I02a are maintained in clutching engagement to provide a driving con nection between the worm gear 43 and the shaft 20 by means of a helical coil spring 43c held under compression between the shouldered end of the sleeve 91 and the shouldered portion of a collar 95 within which the shaft 20 is rotatably disposed.

With the above-described arrangement, the parts I03 and I9a of the clutch actuator 2I function to maintain the clutch teeth 91a disengaged from the clutch teeth I02a so long as the rapid traverse motor I3 is operating to drive or apply torque to the sprocket I9 through the chain I1 and the rotor sprocket I3. Thus, so long as the sprocket I9 is rotated in one direction through operation of the motor I3 or is being reversely driven through the driving connection during a plugging interval against the braking action of the motor I3, the camming surfaces I030 and I04a coact to move the sleeves I03a and 01 to the left along the shaft 20 against the bias of the spring 440 until the stop surfaces I03c and I03d are engaged with the surfaces Ma and i042) respectively. Such engagement of the identified stop surfaces is maintained so long as driving torque is developed between the shaft 20 and the sprocket I0, either during the driving or plugging interval. The extent of such longitudinal movement of the sleeve 31 along the shaft 20 is sumcient to fully disengage the teeth 91a from the teeth Il2a such that the driving'connection between the worm gear 43 and the shaft 20 is completely broken. Accordingly, the feed motor I4 may be operated without effect during a period when the rapid traverse motor I3 is operating to drive one of the two supports I0 and I2 or to plug the support to a stop. Similarly, the camming surfaces I03e and i040 coact to shift the sleeves I03 and 01 to the left to disengage the clutch teeth Ila and I02a when torque is developed between the shaft 20 and the sprocket I0 in the reverse direction, either through reverse rotary movement of the rapid traverse motor I3 to drive one of the two supports, or during operation of this motor to plug the support to a stop. It will thus be apparent that the actuator 2| and the clutch 44 are so arranged that when the rapid traverse motor is energized, the driving connection between the feed motor I4 and the shaft 20 is broken. When, however, the rapid traverse motor is deenergized, the spring 430 acts to shift the two parts 31 and I0! to the right suificiently to produce full engagement of the teeth 01a and I02a, whereby the worm gear 43 is clutched to the shaft 20 to establish a driving connection therebetween. In this regard it is noted that during operation of the feed motor I4 to drive the shaft 20 at slow speed through the gear reduction afforded by the worm 42 and gear 43, the rotor of the motor I3 is driven at a speed somewhat in excess of the speed of rotation of the shaft 20 through the clutch actuator 2I, the sprocket I3, the chain I1 and the sprocket I0.

Position gauging means As best shown in Figures 5, 6, 7 and 8 of the drawings, the gauge and Microswitch assembly associated with the work support I0 is mounted within a housing 33a supported at the top of a bracket member 83 rigidly mounted upon the bed 00 to one side thereof. Specifically, the housing 33a is employed to house the Microswitch 60, the parts of the lever mechanism 61 and a micrometer gauge 04 utilized visually to indicate movement of the work support I0 to a position beyond a particular preselected position. The gauge 04 is provided with the usual actuating plunger 34a arranged for actuation by the lever mechanism 61 through a spring biased actuating rod 34!) slidably supported within a bore through the housing 030. This rod and the actuating plunger a of the Microswitch 60 are adapted for actuation by the two arms 81a and 01b of a lever 31 carried by a pivot shaft 06 suitably journalled in the housing 33a. As best shown in Figure 8 of the drawings, the shaft 86 mounts an actuating arm 05 at its lower end having an end projected into the path of movement of the end micrometer block 66 disposed within the trough 63b of the rail 03. A coil spring 9| (Figure 7) reacting between the housing 03a and a shouldered collar 9Ia fixedly mounted upon the rod 84b acts normally to bias the lever 01 and associated parts 33 and 30 against actuation of the Microswitch actuating plunger 00a and the gauge actuating plunger 04a. This spring bias is counterbalanced by means of an oppositely acting bias assembly p which comprises a spring biased rocker rod 30.

having a slotted end 66!) for seating a cross pin 660 which extends between the lever arms 61a and 61b. The ball end of the sleeve Illa is seated within a ball socket 69 which has a shank extending through the wall of the housing 63a and is internally threaded to receive an assembly screw 66a. A spring 66 surrounding the parts Ila, l6 and 66d and reacting between the shouldered parts 680 and 66b, provides a force acting between the lever 61 and the housing 63a which opposes the oppositely directed force of the spring 6|. Specifically, and as best shown in Figure 7 of the drawings, the force exerted by the spring 66 is along the line offset with respect to the line passing through the center of the. shaft 66 and the center of the ball and socket support for the sleeve 66a. This force tends to rotate the lever 61 in a counter-clockwise direction, whereas the spring 9! acting upon the rod 64b tends to rotate the lever 61 in a clockwise direction. By suitable design of the springs 60 and 9|, these oppositely directed forces may be so proportioned that an absolute zero readingof the micrometer gauge 64, together with bare touching engagement of the lever arm 61a with the actuating plunger 60a of the Microswitch 66, is obtained with the lever 65 completely disengaged from the micrometer blocks 66 carried by the trough 66b. The lever 61 is held in this condition by the greater force of the spring 90 which normally holds the lever arm 61a against an adjustable stop 610, as shown in Figure 7. This stop 61c is threaded into the housing 83a and is adjusted when the machine is set up to properly position the lever arm 65 and its contact point with relation to micrometer switch 60 and the zero reading of the micrometer gauge 64. The lever arm 85 may be moved clockwise, Figure 6. until the pin 66c passes the centerline betweer'i the parts 66 and 88a, whereupon the spring 93 holds said lever arm and its lever 61 in the opposite or out-of-action position indicated by the dotted line position of the lever arm 85. This is for clearance of the blocks 64-66. Manual release of the lever arm 65 from this position causes it to be returned by the spring 90 to the operative position.

As indicated above, the micrometer block or blocks 66, which may be required in causing the desired preselected position to be imparted to the work support ID, are adapted for support within a trough 631) formed along the side of a rail 63 which is fixedly carried by the lower member Illa of the work support Hi. This rail is also provided with a longitudinally extending T-slot 63a which is used in adjustably positioning the micrometer screw support 64 along the trough 63b. Specifically, the micrometer screw 66 is threaded through the support 64, and the support is split and drilled to receive a clamping screw 64a. The threaded shank of this screw extends through the stem of the T-slot 63a to engage the nut 64b adjustable along the cross portion of this slot. With this structure, the micrometer screw support 64 may be obviously moved to different positions along the rail 63 and may be clamped in a selected position through actuation of the clamping screw 64a. At any selected position, the micrometer screw 66 may be adjustably threaded through the support 64 in order accurately to position one or more micrometer blocks along the trough 6312.

For the purpose of providing an approximate indication of the position of the work support ll relative to the axis of rotation of the 15001 spindle Ila, the housing 66a is provided with a projection 62 which is utilized pivotally to support an indicating arm 93. This arm is cooperable with a ruled insert 64 disposed within a recess extending longitudinally of the rail 63 to provide the desired approximate indication of the position of the work support In relative to the tool spindle axis.

In its details, the gauge and Microswitch assembly associated with the' tool support I2 is identical with the assembly just described and 1 provided in association with the work support l6. It is noted, however, that the gauge and Microswitch assembly provided to control the positioning of the tool support I: is mounted upon this support for movement therewith in the manner best illustrated in Figure "10 of the drawings. Actuation of the lever mechanism 610 of this assembly is effected through engagement of the actuating lever 85a embodied in this assembly with a micrometer block 1|. Specifically, these blocks may be stacked one above the other in the number required in the trough 95b of a rail 66 fixedly mounted upon the vertical column 6| in a vertical position. This rail is provided with a rail rib 66a extending longitudinally thereof which is used slidably to support a support 14 for the micrometer screw 13. The micrometer screw 13 is threaded through the support I4,'and the support is split and drilled to receive a clamping screw 14a which is threaded.into a clamping nut 141). With this structure, the micrometer screw support 64 may obviously be moved to diiierent positions along the rail rib 96a and may be clamped in a selected position through actuation oi! the clamping screw 14a. At any selected position of the support 14, this screw may be adjustably threaded through the support 14 for the purpose of accurately positioning one or more micrometer blocks along the trough 9511. Thus, it will be understood that the Microswitch 66 and position indicating gauge of the gauge assembly associated with the tooll support III are adapted for actuation in response to movement of the tool support I! from an elevated position. downwardly to a desired preselected position relative to the work support l6.

Operation of the machine In considering the operation of the machine, it may be assumed that a work piece II has been fixedly clamped to the top of the work support Ill and that two holes H1 and H: are to be bored into this piece along the side facing the'boring spindle Ila. It may be assumed further, that the hole H1 is to be bored at a position located 2.005 inches from the left edge of the work piece and the same distance from the top edge of the piece. With this position determined from available drawings a micrometer block 66 of appropriate length and adjustment oi. the micrometer spindle 65 are required in setting up for automatic positioning of the work support l0 in the desired position. Specifically, with the position of the left edge of the work piece H relative to the work support III known and the position of the work support relative to the axis of rotation of the tool spindle l2a known, the work support may be first accurately positioned to center the rotational axis of the tool spindle in 2.005 inches in from the left edge of the work piece through manual adjustment of the work support to the desired position. Following this, the micrometer screw support 64 is adjusted along the rail 63 to permit a micrometer block of accurate length to be inserted into the trough 03b. The support 04 is next clamped in position and the screw 13 adjusted until the indicating needle of the gauge 04 is exactly at its zero setting. The work support I may now be moved to the left in preparation for automatic positioning of the work support. Similarly, adjustment of the micrometer spindle l0 and the use of one or more micrometer blocks 1| may be required in positioning the tool support I2 to bring the tool spindle |2a into the desired borin position relative to the work piece II.

Assuming that automatic positioning of the work support I0 is to first be effected, the transmission mechanism 24 is shifted through operation of the actuator 40 to a position wherein the teeth of the clutch sleeve 240 are engaged with the teeth of the clutch member 24b, thereby to establish a drivin connection between the shaft 20 and the lead screw 30. Incident to this operation, the uni-control connection U is actuated to shift the selector switch 54 to a position wherein the contacts 00 thereof are closed and the contacts 55 are open.

To initiate the automatic positioning operation, the automatic position switch 59 is momentarily actuated to complete a circuit through the normally closed contacts 0| of the Microswitch 00, the contacts 50 and the contacts of the limit switch 53 for energizing the contactor I and the operating magnet of the timing device I00 in parallel from the current source 49. When thus energized, the contactor Il0 closes it contacts I12 to complete an obvious locking circuit for itself and the operating magnet of the timing device I00. When the magnet 01' the timing device I60 is thus energized, this device operates to open its contacts I82 andthen closes its contacts I63, thereby to prepare a circuit for energizing the rapid plug left contactor IIO. At,

its contacts I'll, the contactor I10, upon operating, connects the terminals 40 of the rapid traverse motor It to the conductors of the threephase current source I0 in the proper phase relationship to effect movement of the work support I0 the right. I

When thus energized, the rapid traverse motor I3 acts to drive the work support I0 to the right through the driving connection afforded by the sleeve I9a, the shaft 20, the engaged gears 22 and 23, the clutch 24, the meshing gears 25, 21 and 20, the lead screw 30, and the screw follower II. The torque thus developed in the shaft 20 causes the clutch actuating parts 2| to function in the manner explained above to disengage the clutch teeth 91a and I02a, ,and thus break the driving connection between the feed motor I4 and the shaft 20. Rapid traverse movement of the work support I0 to the right continues at a speed indicated by the amplitude of the variations in the saw tooth line D shown in Figure 12 of the drawings until it reaches the preselected position indicated at A along this line. At this point, the leading end of the micrometer block 66 engages the actuating lever 00 of the lever mechanism 61 to effect instant operation of the micrometer switch 00 from its illustrated normal position to its of!- normal position wherein the contacts 6| are opened and the contacts 02 are closed. When the contacts 6| are thus opened, the described operating and locking circuits for the contactor I10 and the operatin magnet of the timing device I00 are interrupted.

12 In releasing, the contactor Ill opens its contacts IlI tg'disconnect the motor terminals 40 from tha current source II. At its contacts I12, the contactor I10 opens another point In the locking circuit for itself and the operating magnet of the timer I00. The timer I" now starts to time out and in so doing first closes its contacts I02 to complete a circuit through its contacts I" for energizing the contactor III. In operating, the contactor |I0 closes its contacts III to connect the winding terminals 40 of the rapid traverse motor II to the source I0 with one of the phases thereof reversed; that is, the motor II is energized with current of the proper phase to drive the support I0 to the left. Due to the kinetic energy stored in the moving parts of the driving mechanism, the support I0 and the work piece II, however. the work support continues to move in the same direction beyond the preselected position against the torque developed by the described reverse phase energizetion of the rapid traverse motor II. In other words, the motor I2 acts to brake or plug the moving system to a stop. Incident to such reversal in the direction of the torque developed by the motor II, the clutch actuator 2| is momentarily released to establish a driving connection between the feed motor I4 and the shaft 20, and Is then reactuated to break this connection.

The timer I00 is assigned the function of maintaining the reverse phase energization of the rapid traverse motor I3 only for the interval required to bring the work support I0 to a stop. In this regard it is pointed out that this timer is preferably an adjustable orifice devicesuch that it may be set to measure any desired time interval within certain limits. The structural arrangement is such that its contacts I" are automatically opened a predetermined time interval after its contacts I02. are closed. Accordingly, when the work support I0 is stopped through the plugging action of the rapid traverse motor I2, the contents I02 are opened to deenergize the contactor I I0.

Upon operating in response to closure of the contacts I08 in the manner explained above, the

contactor 0 also closes its contacts II2 to complete a circuit through the engaged contacts 02 of the Microswitch 00 and the break contacts I" of the contactor I30 for energizing the latter contactor. In operating, the contactor I30 first looks up in a circuit which includes its contacts I34, the break contacts I22, the contacts 50 of the selector switch 54 and the contacts of the limit switch 53. Thereafter, the contactor I30 opens its contacts I30 to interrupt its operating circuit. At its contacts I02, the contactor I30 completes a circuit through the contacts H2, 02 and 56 and the contacts of the limit switch 03 for energizing the feed left contactor I40. At its contacts I30, the contactor I 30 prepares an operating circuit for the contactor I00 and a circuit for energizing the operating winding of the timer I00.

The contactor I40, upon operating, closes its contacts I42 to complete a lockingecircuit for itself through the contacts 62 and 50 and the contacts of the limit switch 53. At its contacts I42, the contactor I40 opens a point in the prepared circuit for energizing the windings of the contactor I00 and the timer I00 in parallel. At its contacts I, the contactor I 40 connects the winding terminals 48 of the feed motor I4 to the current source I0, thereby to energize the feed motor with current of the proper phase to drive the work support III to the left back to the preselected position. As explained above, however, duringthe period required to stop the work support I through the plugging action of the rapid traverse motor I 3, the worm gear 43 is declutched from the shaft 20 so that operation of the motor I4 is without effect.

When the work suport I0 is brought to a stop at the point B indicated in the operation chart shown in Figure 12 of the drawings, the motor I3 is deenergized in the manner explained above. The spring 430 now functions to produce engage- 'ment of the clutch teeth 91a and I020. in the manner explained above, thereby to establish a driving connection between the worm 42 and the shaft 20. This drivingconnection results in movement of the work support I0 back to the preselected position A. Movement of the work support in this direction continues at a medium speed indicated by the amplitude of the saw tooth variations E in the chart of Figure 12 until the table is again moved exactly into the preselected position A. When this position is reached, the lever mechanism 61 is actuated under the influence of the spring 9| to effect operation of the Microswitch 60, such that the contacts 62 thereof are again opened and the contacts 6| thereof are reclosed. In response to opening of the contacts 82, the contactor I40 is deenergized and restores. At its contacts I, this contactor disconnects the feed motor winding terminals 48 from the source I6. At its contacts I42, the contactor I40 opens another point in its own locking circuit. At its contacts I43, the contactor I40 closesthe prepared circuit for energizing the operating windings of the contact I80 and the timer I90 in parallel, this circuit also including the contacts I35 of the energized contactor I30, the contacts 8| of the microswitch 00, the contacts 58 of the selector switch 54 and the contacts of the limit switch 53.

At the instant the feed motor I4 is thus deenergized under the control of the contactor I40, the kinetic energy stored in the moving parts of the machine is suflicient to effect carryover movement of the work support I0 to a position approximately .005 inch to the left of the preselected position. The purpose of energizing the contactor I80 and the timer I90 is to energize the feed motor I4, thereby to stop the work support and then bring the work support back to the exact preselected position A. To this end, the contactor I80, in operating, closes its contacts II to connect the slow speed winding terminals 41 of the feed motor I4 to the current source I6 in the proper phase relationship to drive the work support I0 to the right. When the operating winding of the timer I90 is energized, this timer first opens its contacts I92 and then closes its contacts I93, thereby to prepare a circuit for energizing the plug left contactor I20.

As indicated above, the reversed phase energization of the feed motor I 4 serves two purposes. First, the motor I4 acts to brake the work support I0 and the other moving parts of the machine to a stop at approximately the point C along the operating chart shown in Figure 12, following which the motor functions to drive the work support I0 back to the preselected position A at the very slow speed indicated by the amplitude of the saw tooth line F shown in Figure 12. When the work support I0 is thus returned to the preselected position A, the Microswitch 60 is again actuated to effect opening of the contacts GI and reclosure of the contacts 62. When the contacts 8| are opened, the operatingwindings of the contactor I00 and the timer I90 are deenergized. Reclosure of the contacts 82 is without effect. The contactor I80, in releasing, opens its contacts III to deenergize the feed motor I4. Since the work support I0 is moving at an exceedingly slow speed at the time the feed motor is thus deenergized, the carryover movement beyond the preselected position is substantially negligible. From the above description it will be apparent that the support I0 efiectively hunts about the preselected position A at decreasing amplitudes until the final preselected position is attained.

.When the operating winding of the timer I98 is .deenergized, this timer acts to first close its contacts I92 and then opens its contacts I 93 a predetermined time interval thereafter. During this interval the contactor I20 is energized in an obvious circuit and closes its contacts I2I reversely to connect the slow speed winding terminals 41 to the source I8. Thus operation of the motor I4 is initiated in the proper direction to drive the work support I0 to the right. Such operation is continued, however, only for an interval suilicient to relax the driving connection between the motor I4 and the work support I0, i. e. to remove from the work support all forces acting thereon thus leaving this support floating freely upon the bed 00. This interval is measured by the operation of the timer I90 which opens its contacts I93 a predetermined interval following closure of its contacts I92. When the contacts I93 are opened the contactor I20 is deenergized and restores to open its contacts I2I, thereby to deenergize the feed motor I4. Thus, the work support I0 is left standing exactly in the desired preselected position.

When operated in the manner explained above, the contactor I20 opens its contacts I22 to deenergize the contactor I30. Release of the latter contactor is without effect. Following release of the contactor I 20 in the manner explained above, the control circuit 50 is fully restored to normal in readiness for another operating cycle.

In practice, in order to check the accuracy of the indicating gauge and associated connections, the apparatus may be put through the above described operating cycle. This is preferably done at the outset for locating the first position at which the support is to be stopped. If the indicating pointer of this gauge is not indexed exactly with the zero point of the gauge scale, the micrometer screw 65 should be adjusted until an exact zero reading of the gauge 84 is provided. After this adjustment is made, the exact desired relationship between the position 'of the work piece II and the position responsive elements 60 and 84 is established. Moreover, the work piece II carried by the work support I0 is accurately positioned so that the center of the hole HI, which it is desired to bore, is in exact vertical alignment with the axis of the tool spindle I2a. With the work support I0 thus accurately positioned in the desired preselected position, this support may be clamped to the bed in any conventional manner in order to prevent inadvertent movement thereof out of the preselected position. In this position the metal working operation is performed. If the operation is boring, it may be desired to withdraw the boring tool and back the work support away in order to measure the work. Now, upon returning the work support to position again for a following operation, the automatic cycle is repeated, resulting in moving the work support to the exact position which it occupied at the time of the previous boring aunuc l operation. In actual practice the precision of this automatic re-positioning is within .0002" and tests have shown such re-positloning to be within .00002", the latter dimension requiring a light band instrument for measurement.

The manner in which the described positioning facilities may be utilized in moving the tool support I2 to the desired position relative to the work piece II is exactly the same as explained above with reference to positioning of the work support I0. In this regard it will be understood that to condition the positionin facilities for operation of the tool support I2, the clutch actuator 40 is operated to disengage the teeth of the clutch sleeve 24a from the teeth of the clutch sleeve 24b and to effect engagement between the clutch teeth of the two sleeves 24a and 24c. In response to this operation the driving connection between the shaft 20 and the lead screw I0 is broken and a driving connection is established between the shaft 20 and the lead screw 04. Concurrently therewith, the selector switch 54 is operated through the uni-control connection indicated at U in Figure 1 to open its contacts 50 and close its contacts 55, thereby to substitute the Microswitch 60 carried by the tool support I2 for the Microswitch 60 associated with the work support I0 in the control circuit 50. Specifically, shifting of the selector switch 54 to its second setting renders the contacts of the Microswitch 68 operative to perform the same functions as the contacts 6| of the Microswitch 60 and renders the contacts 09 operative to perform the same functions as the contacts 02 of the Microswitch 60 in the sequence of operations referred to above. Thus, the control circuit 50 is fully conditioned to control the rapid traverse and feed motors I3 and I4 in their operation to move the tool support I2 to a position which will bring the axis of the work spindle I2a in exact alignment with the center of the hole HI. This position is established through appropriate use of one or more micrometer blocks II and appropriate adjustment of the microscrew 13 in the manner previously explained. Following these preparatory operations, the automatic position switch 59 may be momentarily actuated to initiate automatic positionin of the tool support II, which positioning proceeds exactly in accordance with the above explanation.

After the axis of the tool spindle I2a has thus been brought into exact alignment with the center of the hole H-I which it is desired to bore, the boring operation may be carried out in an entirely conventional manner. Following the boring operation, or in the course thereof, the work support I0 may be moved back to permit measuring of the inside diameter of the hole. To this end, the work support I0 is first unclamped from the bed 00, following which the clutch actuator 40 is shifted to break the driving connection between the shaft 20 and the vertical lead screw 34, reestablish the driving connection between the shaft 20 and the horizontal lead screw 30 and shift the selector switch 54 to a position wherein its contacts 56 are closed and its contacts 55 are opened. The self-restoring push button switch 51 may now be actuated to complete a circuit through the contacts of the limit switch 5| for energizing the contactor I00. In operating, this contactor closes its contacts IOI to connect the high speed winding terminals 45 of the rapid traverse motor I3 to the source I0 in the proper phase relationship to effect rapid traverse movement of the work support I0 to the left. This l6 movement is continuous so long as the switch I is held in its closed circuit position, but cannot exceed the limit of the travel of the work support I0 to the left. Thus, upon approaching this limit of its range of travel, the work support I0 actuates the limit switch ii to its open circuit position to effect successive deenergization of the contactor I00 and rapid traverse motor II, thereby to arrest movement of the work support I0 in the indicated direction. Normally, the switch 51 will be released before the limit switch 5I is operated. When released, the operating circuit for the contactor I00 is opened to effect release of this contactor and deenergization of the motor I3, thereby to arrest movement of the table III to the left away from the preselected position.

After the described hole measuring operation is completed the work support I0 may be moved back to the preselected position by again actuating the automatic position switch 59 to initiate the above described sequence of operations, it being noted that movement of this support is arrested only when the support is returned exactly to the preselected position wherein'the center of the hole H--I is in exact alignment with the axis of rotation of the tool spindle Ila.

If it is desired to move the work support I0to the right to a position falling short of the preselected position, this may be accomplished by actuation of the self-restoring push button switch 50, assuming that the clutch 24 is maintained in a postion wherein the driving connection isestablished between the shaft 20 and the horizontal lead screw 30. When this switch is operated, a circuit is completed through the contacts 0| and 50, and the contacts of the limit switch 51 :for energizing the contactor I50. In operating, this contactor closes its contacts I5I to connect the high speed winding terminals 45 of the rapid traverse motor I0 to the source I6 in the proper phase relationship to drive the work support III to the right. Such movement of the work support I0 continues until the switch 50 is released or until the Microswitch 60 is operated to open its contacts GI through actuation of the lever mechanism 61 by the micrometer block or blocks 00. In either case, the contactor I50 is deenergized and opens its contacts IN to deenergize the rapid traverse motor I3 and thus arrest movement of the work support I0. Thus, it will be apparent that the Microswitch 00 serves to prevent the work support I0 from being moved to the right substantially beyond the preselected position. Return movement of the work support to the left to a position wherein the automatic positioning facilities may be effectively used in returning this support to its preselected position, may of course be obtained in response to actuation of the push button switch 51 in the manner explained above.

Movement of the work support I0 to the right beyond the limit of its range of movement is prevented, independently of the Microswitch 50, through the action of the limit switch 50. Specifically, this switch is arranged to open a point in the common portion of the circuits for energizing the contacts I00, I40, I50, I10 and I00 and the operating windings of the two timers I60 and I00 when it is actuated in response .to movement of the work support I0 through the right limit of its range of travel. Interruption of any completed one or ones of these circuits serves to arrest movement of the work support I0 to the right in a manner fully apparent from an inspection of the circuit.

.boring of the hole H|.

The manner in which the tool support l2 may be operated independently of the automatic positioning facilities and under the selective control of the contactors I and I50 and their associated energizing switches 5'! and 58 at a time when the clutch mechanism 24 is appropriately shifted to establish a driving connection between the shaft and the vertical lead screw 34 is exactly the same as explained above. In this regard it is pointed out that the limit switch 52 serves the function of preventing the tool support l2 from being moved beyond the lower limit of its range of travel and thus corresponds in function to the limit switch 53.

After the hole H-l has been bored, additional holes may be bored as desired in accurately spaced relationship relative to the hole H-l. For example, if it is desired to bore a hole H! the center of which is horizontally aligned with the center of the hole H-l but is spaced therefrom a distance of 2.003 inches, the work support i0 is first moved to the left approximately 2 inches to provide a space for insertion of a micrometer block in the trough 63b between the end of the block 66 and the engageable end of the lever 85. This added block is accurately set to measure exactly 2.003 inches between the end surfaces thereof. After being positioned in the trough 63 ahead of the micrometer block or blocks used in the first hole drilling operation, the switch 59 may be momentarily operated to effect operation of the automatic positioning facilities in the manner explained above. In this case the work support I0 is stopped exactly 2.003 inches ahead of the position which it previously occupied during Accordingly, after the work support I0 is clamped to the bed 80, the second hole H2 may be bored in the usual manner. If, after boring the hole H2, it should be desired to reposition the hole H--l in alignment with the boring tool, this may be accomplished by merely removing the added micrometer block of 2.003 inch length from the trough 63 and again actuating the automatic positioning switch 58. In response to this operation the positioning facilities function to return the work support ID to the initial preselected position wherein the center of the hole H-l is in exact alignment with the axis of rotation of the tool spindle Ho. The above described hole boring operations may be repeated to produce as many holes as desired which may be in horizontal or vertical alignment or may be spaced both vertically and horizontally. In any case, however, the described automatic positioning facilities serve to insure exact vertical and horizontal spacing of the centers between the holes bored.

In actual practice of the invention as applied to a boring and milling machine such as shown in the drawings, the rate of travel of the work support when propelled by the rapid traverse motor in the rapid traverse portion of the cycle at D, Figure 12, is 49" per minute. This rapid traverse rate may be varied, as is cutomary in machine tool practice, to suit the particular type of machine or the nature of the work. The fast feed rate of the support when propelled by the feed motor operating at 1200 R. P. M. as noted at E, is .7" per minute. noted at F, is .24 per minute. These rates are illustrative of the principle of operation as applied in the present machine, and it should be understood that the invention may be applied in many modifications. For example, any equiv- The slow feed rate push-button control either with or without rapid traverse movement of the support, or such automatic positioning may be under full automatic control as disclosed herein. Furthermore, the invention in its broader phase contemplates automatic positioning without reversal of travel of the support. That is, it contemplates any suitable approach of the support toward the ultimate point, then reduction by one or-more stages to the desired low rate of feed, and then plugging of the motor into reverse as in the final operation of the full cycle above described. In other words, the cycle may be varied prior to this final operation. This final operation accomplishes a new result in that the plug to reverse serves to relieve and relax all strains on the mechanism, leaving thesupport at rest in the ultimate position. This final operation may be performed in the broader phase of our invention, regardless of whether the feed is reversed to correspondingly move the support. The last slow feed, terminating in plug of the motor to reverse, brings th support to the preselected point and eliminates any tendency of the support to coast forward or beyond such ultimate position. It also avoids any tendency of the support against displacement from stress or strain in the driving train. The support is, therefore, located to a high degree of precision in the predetermined position. clamped in this position by suitable clamping means. In embodiments wherein there is one or more reverse feeds of the support a further advantage results from the final reverse movement which serves to smooth the oil film between the support and its ways and thereby promote greater accuracy in the final location of the support.

While we have shown what is at present considered to be a preferred embodiment of the invention, it will be understood that various modifications may be made which are within the true spirit and scope of the invention as defined in the appended claims.

We claim:

1. In a machine tool, a tool or work support movable to a preselected position, means for moving said support, and means controlled by movement of said support for controlling said moving means to repeatedly reverse the direction of movement of said support in moving said support into said preselected position so as effectively to hunt about said preselected position.

2. In a machine tool, a tool or work support movable to a preselected position, motor means moving said support, driving means providing a driving connection between said motor means and said support, and means controlled by move ment of said support for controlling said motor means repeatedly to reverse the direction of movement of said support in moving said support into said preselected position and to decrease the speed of movement of said support each time the direction of movement thereof is reversed.

3. In a machine tool, a tool or work support movable to a preselected stationary position, motor means for moving said support, driving means providing a driving connection between said motor means and said support, means for controlling said motor means to reverse the direction of movement of said support in moving.

The support should immediately be a 19 said support into said preselected position, and means responsive to movement of said support into said preselected position for controlling said motor means to relax said driving connection.

4. In a machine tool, a tool or work support movable to a preselected stationary position, motor means for moving said support, driving means providing a driving connection between said motor means and said support, means controlled by movement or said support for controlling said moving means to repeatedly reverse the direction of movement of said support in moving said support into said preselected position, and means responsive to movement or said support into said preselected position for controlling said motor means to relax said driving connection.

5. In a machine tool, a tool or work support movable to a preselected stationary position, motor means for moving said support, driving means providing a driving connection comprising a plurality of gears and interrelated driving means between said motor means and said support, means for controlling said motor means to move said support into said preselected position, and means responsive to movement of said support into said preselected position tor relaxing said driving connection.

6. In a machine tool, a tool or work support movable to a preselected stationary position, motor means for moving said support, driving means providing a driving connection compris- 3 ing a plurality of gears and interrelated driving means between said motor means and said support, means for controlling said motor means to move said support into said preselected position, and means responsive to movement of said support into said preselected position tor controlling said motor means to relax said driving connection.

I. In a machine tool, a tool or work support movable to a preselected stationary position, motor means for moving said support, driving meam providing a driving connection between said motor means and said support, means for controlling said motor means to reverse the direction of movement of said support in moving said support into said preselected position and to decrease the speed 01' movement of said support incident to reversal in the direction movement thereof, and means responsive to movement of said support into said preselected position tor controlling said motor means to relax said driving connection.

8. In a machine tool, a tool or work support movable to a preselected position, motor means ior moving said support, driving means providing a driving connection between said motor means and said support, means controlled by movement or said support for controlling said moving means to repeatedly reverse the direction oi movement of said support in moving said support into said preselected position and to decrease the speed of movement of said support each time the direction of movement thereof is reversed, and means responsive to movement of said support into said preselected position for controlling said motor means to relax said driving connection.

9. In a machine tool. a tool or work support movable to a preselected position, motor means for moving said support, driving means providing a driving connection between said motor means and said support. means for energizing said motor means to move said support through said preselected position in one direction, means responsive to movement of said support into said position for controlling said motor means to plug said support to a stop and then reversely move said support through said position, and means responsive to the reverse movement of said support into said position (or controlling said motor means to plug said support to a stop and then reversely move said support back to said position.

10. In a machine tool, a tool or work support movable to a preselected position, motor means for moving said support, driving means providing a driving connection between said motor means and said support, means for energizing said motor means to move said support through said preselected position in one direction, means responsive to movement oi said support into said preselected position for controlling said motor means to plug said support to a stop and then reversely move said support at reduced speed through said preselected position, and

means responsive to the reverse movement oi said support into said preselected position for controlling said motor means to again plug said support to a stop and then reversely move said support back to said preselected position at a still slower speed.

11. In a machine tool, a tool or work support movable to a preselected position, motor means for moving said support, driving means providing a driving connection between said motor means and said support, means for energizing said motor means to move said support through said preselected position in one direction, means responsive to movement 01' said support into said position for controlling said motor means to plug said support to a stop and then reversely move said support through said position, means responsive to the reverse movement oi said support into said position for controlling said motor means to plug said support to a stop and then reversely move said support back to said position, and means responsive to said movement of said support back to said position for relaxing said driving connection.

12. In a machine tool. a tool or work support movable to a preselected position, motor means ior moving said support, driving means providing a driving connection between said motor means and said support, means for energizing said motor means to move said support through said preselected position in one direction, means responsive to movement of said support into said preselected position for controlling said motor means to plug said support to a stop and then reversely move said support at reduced speed through said preselected position, means responsive to the reverse movement 01' said support into said preselected position for controlling said motor means to again plug said support to a stop and then reversely move said support back to said preselected position at a still slower speed, and means responsive to said movement oi said support back to said position for controlling said motor to relax said driving connection.

13. In a machine tool, a tool or work support movable to a preselected position, reversible rapid traverse and feed motors ior driving said support at iast and slow speeds respectively, driving means providing driving connections between said motors and said support, means for energizing said rapid traverse motor to move said support through said preselected position in one direction, means responsive to movement of said support into said preselected'position for energizing said rapid traverse motor to plug said support to a stop and for energizing said feed motor to drive said support toward said preselected position in the reverse direction, means for deenergizing said rapid traverse motor when movement of said support is stopped, and clutch means included in said driving means and operafive to establish a driving connection between said feed motor and said support only in response to deenergization of said rapid traverse motor.

14. In a machine tool, atool or work support movable to a preselected position, reversible rapid traverse and feed motors for driving said support at fast and slow speeds respectively, driving means providin driving connections between said motors and said support, means for energizing said rapid traverse motor to move said support through said preselected position in one direction, clutch means included in said driving means to break the driving connection between said feed motor and support in response to energization of said rapid traverse motor, means responsive to movement of said support into said preselected position for energizing said rapid traverse motor to plug said support to a stop and for energizing said feed motor to drive said support through said preselected position in the reverse direction. means for deenergizing said rapid traverse motor when movement of said upport is stopped, whereby said clutch means is operated to reestablish the driving connection between said feed motor and said support, and means responsive to reverse movement of said support into said preselected position for energizing said teed motor to plug said support to a stop and then reversely move said support back to said preselected position.

15. In a machine tool, a tool or work support movable to a preselected position, reversible rapid traverse and feed motors for driving said support at fast and slow speeds respectively, driving means providing driving connections between said motors and said support, means for energizing said rapid traverse motor to move said support through said preselected position in one direction, clutch means included in said driving means to break the driving connection between said feed motor and support in response to energization of said rapid traverse motor, mean responsive to movement of said support into said preselected position for energizing said rapid traverse motor to plug said support to a stop and for energizing said teed motor to drive said support through said preselected position in the reverse direction, means for deenergizing said rapid traverse motor when movement of said support is stopped, whereby said clutch means is operated to reestablish the driving connection between said feed motor and said support, means responsive to reverse movement of said support into said preselected setting for energizing said feed motor to plug said support to a stop and then reversely move said support back to said preselected position, and means responsive to movement of said support back to said preselected position for controlling said teed motor to relax the driving connection between said feed motor and said support.

16. In a machine tool, a tool or work support movable to a preselected position, a rapid traverse motor for driving said support at a high speed, a reversible two speed feed motor for driving said support at a slower speed, driving means providing driving connections between said motors and said support, means for energizing said rapid traverse motor to move said support through said preselected position in one direction, clutch means included in said driving means to break the driving connection between said feed motor and support in response to energization of said rapid traverse motor, means responsive to movement of said support into said preselected position for energizing said rapid traverse motor to plug said support to a stop and for energizing said teed motor for its highest speed operation to drive said support through said preselected position in the reverse direction, means for deenergizing said rapid traverse motor when movement of said support is stopped, whereby said clutch means is operated to reestablish the driving connection between said feed motor and said support, means responsive to reverse movement of said support into said preselected position for energizing said feed motor for slow speed operation in the re:- verse direction, thereby to plug said support to a stop and then reversely move said support back to said preselected position, and means responsive to movement of said support back to said preselected position for energizing said feed motor for limited reverse slow speed operation, thereby to relax the driving connection between said feed motor and said support.

17. In a machine tool, a tool or work support movable to a preselected position, a reversible two speed rapid traverse motor for driving said support at high speed, a feed motor for driving said support at a slower speed, a position responsive switch operated each time said support is moved through said preselected position, means in part controlled by said switch for successively effecting slow speed operation of said rapid traverse motor and operation of said feed motor to move said support into said preselected position, a second switch, a circuit controlled jointly by said switches, and means included in said circuit for controlling said rapid traverse motor to efiect high speed movement of said support in one direction to an eigtent limited by the operation of said position responsive switch.

18. In a machine tool, a tool or work support movable to a preselected stationary position, motor means for driving said support, a position responsive switch operated each time said support is moved through said preselected position, means in part controlled by said switch for controlling said motor means to move said support into said preselected position, a second switch, a circuit jointly controlled by said switches, and means included in said circuit for controlling said motor means to efiect movement of said support in one direction to an extent limited by the operation of said position responsive switch.

19. In a machine tool, a tool or work support movable to a preselected position, reversing motor means for driving said support, and a position responsive switch arranged for controlling said motor means and actuated in response to movement of said support to eifect plugging the motor means to reverse the direction of movement of said support to eiIect the final movement of the support to its ultimate position and to relax the driving connection between said motor means and said support.

20. In a machine tool, a tool or work support movable to a preselected position, motor means for moving said support, driving means providing a drive connection between said motor means and said support, and means responsive to movement oi said support ior controlling said motor means to move said support into said preselected position including a control circuit for said motor means having a stationary limit switch, lever mechanism actuated by movement of said support and arranged to actuate said limit switch, a micrometer gauge coacting with said limit switch and said lever mechanism, and means responsive to movement of said lever mechanism upon movement of said support into said preselected position for relaxing said driving connection.

21. A machine tool as set forth in claim 20, in which the lever mechanism includes a lever arm arranged to be actuated by a micrometer block or the like carried on the support, a lever arm arranged Ior actuating said micrometer gauge, and a lever arm arranged for actuating said limit switch.

22. A machine tool as set forth in claim 20, in which the lever mechanism includes a lever arm arranged to be actuated by a micrometer block or the like carried on the support, a lever arm arranged for actuating said micrometer gauge, and a lever arm arranged for actuating said limit switch; and means (or biasing the lever mechanism to a zero reading position the micrometer gauge.

23. A machine tool as set forth in claim 20, in which the lever mechanism includes a lever arm arranged to be actuated by a micrometer block or the like carried on the support, a lever arm arranged for actuating said micrometer gauge, and a lever arm arranged for actuating said limit switch, and means for biasing the lever mechanism to a zero reading position oi the micrometer gauge, said biasing means arranged to exert biasing iorces in opposite directions, one to said zero reading position and the other to hold the first mentioned lever arm in a position removed from the path 0! said micrometer block.

24. In a machine tool, a tool or work support movable to a preselected position, motor means for moving said support, driving means providing a drive connection between said motor means and said support, and means responsive to movement of said support for controlling said motor means to move said support into said preselected position including a control circuit for said motor means having a stationary limit switch, lever m:chanism actuated by movement of said support and arranged to actuate said limit switch, a micrometer gauge in co-action with said limit switch and said lever mechanism, and means responsive to movement of said lever mechanism upon movement oi said support into said preselected position for releasing said driving connection, said lever mechanism including a lever arm arranged to be actuated by a micrometer block or the like carried on the support, a lever arm arranged for actuating said micrometer gauge, and a lever arm arranged for actuating said limit switch, and means for biasing the lever mechanism to a zero reading position of the micrometer gauge, said biasing means arranged to exert biasing forces in oppcsite direction, one to said zero reading position and the other to hold the first mentioned lever arm in a position removed from the path of said micrometer block.

25. In a machine tool, a work support movable to a preselected position, a tool support movable to a preselected position in a plane transverse to said work support movement, a feed motor, a rapid traverse motor, drive gearing arranged for optional connection between said feed motor and either said work support or said tool support and comprising a driving worm meshing with a worm gear and a displaceable clutch element driven by said worm gear, and an overrunning drive connection from said rapid traverse motor to said drive gearing arranged to overrun the drive from the feed motor and to drive either the work support or the tool support at the rapid traverse rate, said over-running drive connection being arranged to eil'ect displacement 01' said clutch element when a torque is transmitted from said rapid traverse motor to said support.

26. In a machine tool. a tool or work support movable to a preselected position, a rapid traverse motor and a feed motor for driving said support at fast and slow speeds respectively, driving means providing driving connections between said motors and said support, means for energizing said rapid traverse motor to move said support in a direction approaching said preselected position, and means responsive to rapid traverse movement 01' said support to energize said feed motor to drive s.,id support toward said preselected position, to eflect stopping of said support at said preselected position, and to relax the driving connection between the feed motor and the support, said driving means including an overrunning clutch between the rapid traverse motor and the drive to said support arranged to overrun the driving means from the feed motor.

27. In combination, a tool or work support movable to a preselected position, means for moving said support, means for causing said support automatically and accurately to assume said preselected position comprising reversing means for reversing the direction of movement of said support in moving toward said preselected position, said reversing means being actuated just as said support reaches said preselected position, whereby the inertia of said moving support causes it to move beyond said preselected position, and means for decreasing the speed of movement 01' said support incident to operation of said reversing means.

28. For use with a machine of the type having a movable tool or work support and power means for moving said support, automatic positioning control means for accurately stopping said support at a preselected position comprising, power means reversing means, multispeed control means for causing said power means to move said support at different predetermined speeds, and support position responsive means controlling said reversing means and said multispeed control means when said support is in proximity to said preselected position to reverse the direction of movement of said support and to change the speed at which said support is moved prior to stopping said support at said preselected position.

29. For use with a machine of the type having a movable tool or work support and power means for moving said support, automatic positioning control means for accurately stopping said support at a preselected positioncomprising, power m,ans reversing means, control means for rendering said power means ineffective to move said support, multispeed control means for causing said power means to move said support at different predetermined speeds, and support position responsive means controlling said reversing means said control means and said multispeed control means and operative when said support is in proximity to said preselected position to reverse the direction of movement of said support and simultaneously therewith to vary the speed of said support, and then to terminate the drive of said support to stop said support at said preselected position.

30. In combination, a tool or work support movable to a preselected position, multispeed multidirection power means for controlling the movement of said support, and support position responsive means for repeatedly changing the di rection and speed of movement of said support when in proximity to said preselected position prior to stopping said support accurately at said preselected position.

31. In combination, a movable tool or work support, multispeed power means for moving said support, automatic positioning control means for accurately stopping said support at a preselected position comprising power means reversing means, control means for rendering said power means ineffective to move said support, support position responsive means controlling said reversing means and said control means operative when said support is in proximity to said preselected position to reverse the direction of movement of said support and then to terminate the drive of said support to stop said support at said preselected position, and means for decreasing the speed of movement of said support simultaneously with the reversal of direction of movement thereof.

32. In a combination, a movable element movable to be stopped with a, high degree of accuracy at a preselected position relative to a fixed support, motor means for moving said element, driving means providing a, driving connection between said motor means and said element, means for controlling said motor means to reverse the direction of movement of said element in moving said element into said preselected position relative to said support, means for actuating said last mentioned means when said element moves into proximity of said preselected position, and means responsive to stopping of said element in said preselected position for promptly causing deenergization and stopping of said motor.

33. Apparatus for automatically positioning to a high degree of accuracy a movable member at any position along a particular path of travel relative to a fixed support, comprising, motive means for moving said member in one direction along said path at relatively fast and slow rates of speed and for reversing the direction of movement of said member along said path, selecting means for preselecting the ultimate position of said member along said path, control means for controlling said motive means, means for rendering said control means effective to cause a reversal of said motive means in response-to movement of said movable member in one direction along said path at said relatively fast rate of speed into proximity of said ultimate position as determined by the setting of said selecting means and for thereafter causing said member to approach said ultimate position from the opposite direction, and means incident to changing the direction of movement of said member along said path for also changing its speed of movement from said fast rate to said slow rate,

34. Apparatus for automatically positioning to a high degree of accuracy a movable member at any position along a particular path of travel relative to a fixed support, motor means for moving said member, driving means providing a'driving connection between said motor means and said member, reversing means for reversing the direction of movement of said member by said motor means, selecting means for preselecting the ultimate position of said member relative to said support, control means for controlling said motor, means to move said member at fast and slow speeds including an actuable element for rendering said control means effective to perform a control function on said motor means, means for causing said actuable element to render said reversing means eflective, means for effectively positioning said actuable element at said ultimate position, and means responsive to movement of said member through said ultimate position of operating said actuable element to render both said reversing means and said control means effective whereby said member moves back toward said ultimate position from the opposite direction and at a different speed than when it first moved through said ultimate position.

CHARLES B. DE VLIEG. EUGENE E. S'I'EGNER.

REFERENCES CITED The following references are of record in the I file of this patent:

UNITED STATES PATENTS Number Name Date 1,323,267 Hanson Dec. 2, 1919 1,757,929 Shaw et al May 6, 1930 1,942,209 Graves et al. Jan. 2, 1934 1,988,267 Dumser Jan. 15, 1935 2,007,180 Doran et a1 July 9, 1935 2,029,335 Oberhoffken et a1. Feb. 4, 1936 2,123,825 De Vlieg July 12, 1938 2,134,743 Strawn Nov. 1, 1938 2,142,439 Forward Jan. 3, 1939 2,158,649 Armitage May 16, 1939 2,198,102 Armitage Apr. 23, 1940 2,224,107 Ridgway Dec. 3, 1940 2,329,756 Granberg et a1. Sept. 21, 1943 2,339,435 Stephan Jan. 18, 1944 2,370,222 Bennett et al Feb. 27, 1945 2,398,346 Anderson Apr. 16, 1946 

